Flat-panel detectors are used in modern x-ray image recording devices of this type. Over the years, these have replaced the previously used image amplification systems. With these earlier image amplification systems, it was necessary to keep the distance between the patient and the image amplifier as minimal as possible, since the radiation dose needed to achieve an adequate image increases quadratically with the distance of the image amplifier from the x-ray source. In terms of the number of impacting photons, as small a distance as possible between the patient and the flat panel detector would also be advantageous with the use of flat panel detectors. The operating personnel, particularly if he/she has learnt to operate the x-ray image recording devices on such with the image amplification systems, still tend to select such settings, whereby the distance between the patient and the flat panel detector is as small as possible.
The question arises as to whether an optimal image quality is always achieved. Furthermore, the exposure dose of an operating person by means of scatter radiation, which was previously absorbed in the detector, is also to be minimized.